Dairy farmers might describe their ideal dairy cow as early maturing with a first lactation before 24 months, easy calving, good milk production, easy to breed back, good udder, good feet and legs and disease resistant.

“These traits turn into longevity and keep cows around for a long, productive life,” said Dr. Brad Hines, professor of dairy management at the University of Minnesota.

Unfortunately, the heavy use of limited sires within the major dairy breeds has resulted in inbreeding. “It’s been a problem for a long time,” said Hines, noting that inbreeding has led to numerous and costly issues including reduced fertility and increased stillbirths. “Some of the effects are masked – cows are pregnant, then 60 days later lose the pregnancy. There are more haplotypes (DNA variants along a single chromosome) showing up – are emerging calf issues in Holsteins related to inbreeding? I think we will see more issues like this as time goes by.”

Hines explained that dairy farmers started to crossbreed to avoid inbreeding.

In the past, geneticists said that a 6.25% inbreeding coefficient was the threshold no one wanted to cross because that’s when deleterious effects such as reduced fertility and reduced calf survival appeared.

“In 2000, Holstein inbreeding coefficients were about 4.5%,” said Hines. “Today, the number is around 10.5%. Jerseys’ coefficients have increased as well, but not as quickly.”

Because inbreeding coefficients are still increasing, the dairy industry has turned to more crossbreeding.

Hines began crossbreeding studies about 25 years ago. “We first used Jerseys because that’s what the dairy industry was using for calving ease, especially on Holstein heifers,” he said. “We didn’t want to breed back to Holstein or Jersey because then you get a three-quarters crossbred that doesn’t perform as well as a two-breed cross or the main breed. We started breeding to Montbéliarde, always looking for ‘what to breed the crosses to.’”

The VikingRed, which replaced the Jersey in three-breed rotation research, was another breed used in the program. That three-breed rotational cross is known as ProCROSS, and includes Holstein, VikingRed and Montbéliarde. For grass-based production systems, Hines recommends a cross that includes Jersey, VikingRed and Normande.

“By the time they reached third calving, 64% of Jersey x Holstein crosses calved a third time versus 50% of Holsteins,” said Hines. “Jersey x Holstein crosses had lower body weight – about 123 to 180 pounds lighter than a Holstein. In third lactation, these cows weighed about 1,200 pounds, had higher BCS and days open was better at 24 to 42 days.”

Protein and SCC weren’t much different in first lactation cows, but as Jersey x Holsteins aged, they couldn’t keep up with Holsteins’ production.

“The biggest thing we noticed was udder clearance,” said Hines. “We measured all cows from bottom of the parlor floor to the bottom of the rear udder and noticed less clearance in Jersey x Holstein crosses, which translates to deeper udders. That has lot of implications, but we’re seeing less of that because people are using better Jersey bulls for crosses.”

Hines said two-breed crossbred cows remained in herds at least one year longer than Holsteins, which translates to increased lifetime profit. Montbéliarde and VikingRed cows had higher daily profit per day, and crossbreds had lower overall health costs.

Since many cows leave the herd due to health reasons, researchers tracked health costs of crossbreds and compared Holsteins, two-breed crosses and three-breed crosses. Health treatments for first lactation Holsteins averaged about $43/cow. Two-breed and three-breed crosses had lower health costs than Holsteins in first lactation. Second lactation Holsteins had higher health cost at around $75/cow. Health costs for third lactation purebred Holsteins averaged $109/cow, and health costs for third lactation crossbred cows were lower.

Hines emphasized the value of thoughtful crossbreeding, which he described as a mating system that complements breed improvement.

“Select the best AI bulls within a breed to increase genetic improvement,” he said. “Heterosis is what you get on top of genetic improvement: 3% for some breeds, 10% for some of the Alps breeds. There are advantages for fertility, health and survival.”

To optimize hybrid vigor, Hines suggests using three breeds. “Two breeds in a flip-flop system limits hybrid vigor,” he said. “Hybrid vigor is where we see the advantages in fertility, lower health costs and lower feed costs. Using four breeds limits the influence of individual breeds and can become complicated.”

While New Zealand dairy farmers have successfully used F1 sires, Hines isn’t a fan of crossbred bulls. “It worked in New Zealand because they developed a composite breed – the KiwiCross™ (Holstein x Jersey),” he said. “The problem is in the U.S., if you breed a Jersey x Holstein bull to a Holstein cow, you’re not going to get a two-breed cross. It depends on which genes you get from the crossbred bull. You might get all Jersey, or all Holstein. If you breed a two-breed cow to a Jersey x Holstein bull, you could get a three-quarters Jersey or a three-quarters Holstein.”

He added that genetic evaluations show much better net merit values for purebred bulls compared to crossbred bulls.

What about a rotation that includes breeding three-breed cross cows to a Holstein bull every other generation? Hines said one disadvantage of such a system is less hybrid vigor, which negates the goal of crossbreeding.

“If you’re adding Holstein every other generation, you don’t get the hybrid vigor you’d get by using Holstein in a rotation,” he said. “It’s crossbreeding, but it doesn’t work as well because the breeds aren’t necessarily complementing each other. It’s about complementing all the breeds in a rotation.”

Although there have been significant genetic improvements in all the major dairy breeds, Hines said there aren’t enough changes in Holsteins to lessen the importance of crossbreeding.

“As inbreeding goes up, at some point, fertility is going to go down and there will be decreased health,” he said. “We won’t have a choice other than crossbreeding. I’m not convinced we can select our way out of it in any of the (pure) breeds.”

by Sally Colby